Process of producing silicon carbid.



F. J. TONE. PROCESS OF PRODUCING SILICON CARBID.

-APPLICATION FILED JUNE14, 1907.

1,044,295, Patented Nov. 12, 1912.

FRANK J. TONE, OF NIAGARA FALL-S, NEW YORK.

PROCESS OF PRODIICING SILICON CABBID..

Specification of` Letters Patent.

Patented Nov. 1 2, 1912.

Application filed June 14, 1907. Serial No. 379,035.

T o all whom, it mayfconrn: i a

Be it known that I, FRANK J. TONE, al citizen of the United States,residing at-l Niagara Falls, in the county of Niagara and State of NewYork, have invented certain new and useful vImprovements in Processes ofProducing Silicon Carbid, of which the following is a specification. vThis invention relates to the manufacture of silicon carbid and has forits object the increasing of the efficiency of the process and theoutput of the furnace.

In the commercial manufacture of silicon, carbid almixture of silica andcarbon is subjected to heat in an electric furnace, the heating meansbeing a resistance-core ofgranular or pulverized carbon. This coreoffers resistance not only by reason of the specific resistance of thecarbon but also on account of the numerous points of poor contactbetween the discrete particles of carbon.

I have discovered that the efliciency of. the process may beconsiderably increased by employing in place of the core of pulverizedor granular carbon a continuous solid carbon corel consisting either ofa .single shapedpiece Y"or a series ofl pieces joined together in amanner to form the equivalentof a single piece. l

Referring to the accompanying drawing, in which each of the figures is ahorizontalv section of a charged furnacez-Figure l shows a straight coreconsisting of a single. long carbon rod; Fig. 2 shows a straight i' corebuilt up of a series of joined pieces; and,

Fig. 3b shows azigzag core built up of a series of joined pieces.

The furnaces illustrated have end walls l and side walls 2, of firebrick. Carbon terminals 3 extend through the end walls.

The resistance core 4 shown in 'Fig'. l consists of a single long carbonrod, the section and length of the rod being proportioned to give theproper resistance for the voltage and current at which the furnace is tobe operated. The ends of the core are connect cd to the inner ends ofthe carbon terminals by layers of pulver-ized carbon 5. The charge 6completely fills the receptacle and surrounds the core.

It is difiicult to obtain carbon rods long. enough so thatthe properresistance can be conveniently obtained without increasing the length ofthe furnace beyond practical limits. "I therefore show in Fig; 2 amodified core, which consists of a series of two ,in ahorizontalposition and supported or more rods or pieoesfl joined end to end bymeans ofv closel -fitting carbon collars 7.. The resistances o thecontacts are thus practically eliminated and the series of rods becomesthe ractical equivalent of a single rod without joints.

The core shown in Flg. 3 consists of a series ofl pieces 4 disposed in azigzag path from one termlnal to theother and joined end .toend'by'carbon blocks 8 into which the yends of the pieces are screwed.By this arrangement the length of the core is increased. withoutincreasing the length of the furnace,- ythus making it possible toexpend a. greateramount of energy in the saine space and obtain acorresponding increase in efiiciency.

The several cores are preferably arranged b r the charge,'as separatecore-supports restinig lon the base of the furnaces afford directjjpaths for the escape of heat and decrease f ythe current-eiliciency.

This process offers important advantages over that usin `the pulverizedor granular core. These a vantages are due principally to the changedthermal conditions and will be apparent upon consideration of the fur!nace at the end of the run. cupyingthe central zone of the furnace, is

The core, oc-

then surrounded by a zone of silicon carbid whlch 1n turn 1s surroundedby a zone of partially reduced or unreduced charge-ma- --ter1als. Thespecific reslstance of granular or pulverized carbon isapproXimatcly'fifty times that of solid carbon. The solid core thereforewill occupy-much less space in the furnace and the same -volume ofsilicon carbid will hecomprised in a much smaller lzone in the case ofthe solid core than in Vthe case of the granular core, and the outersurface-in this zone, which is the surface of the non-productive heatdiffusion, will be less.A In other words the losses by radiation will bereduced and the output will he correspondingly increased.v Anotherthermal radvantage is that the mass ofr core-material to he heated tothe high temperature of reaction is much less in the case of the solidcore than the granular core. Heat thus expend ed is non-productive'orlost heat, only the heat conducted from the core to the charge being`productive. Still another gain in thermal efficiency is that the heatexpended in the mass of unrcduced charge surround` ingr the smallersilicon carbid zone of the solidcore furnace is less than that expendedi inthe granular core furnace.

Thesolibd core is convenient to place in the furnace and does notVcontaminatev the nished product as does pulverized o`r granular carbon.The product is better.-and more abundantly produced than with a granularcore.

I claim: l

l. The process ofproduc'ing silicon carbid,'fWhich consists, inembedding in a charge 1 of silicious and carbonaceous materials acontinuous solid resistance-core consisting of a] series o Jiolnedshaped reslstanceieces and assin an electric current through said core.

2. The process of producingv silicon carbid, which consists inVembedding iny a charge of slliclous and. carbonaceous mate' rials acontinuous solid resistance-core consisting off a series of joinedshaped resistance-pieces` supported by the chargeL'and passing anelectric current through said core.

43.The process'of producing silicon carbid, which consists in embeddingina charge of silicious and carbonaceous materials a continuous solidresistance-core consisting of a series of joined shapedresistance-pieces arranged in a circuitous path between the terminals,and passing an electric currentl through said conductor.

In testimony WhereofV/I aiix my signature in presence of two Witnesses.

FRANK J. TONE.

i Witnesses:

1 FRED I. Pinnen,

CHARLES CHORMANN.

